Monomeric phosphinoboranes

The key developments in the chemistry of R2PBR'2 over the last 20 years are reviewed. The categorization of phosphinoboranes as R2PBR'2 species and borylphosphines as R2PBR'2 species is suggested based on an analysis of the literature X-ray crystal structures. The chemistry of derivatives of the simplest borylphosphine H<inf>2</inf>PBH<inf>2</inf> is discussed. Six methods of preparation of R2PBR'2 are presented along with the reactions of the products with H<inf>2</inf>, amine-boranes, elemental chalcogens, Me<inf>3</inf>NO and compounds featuring CO, CC and CN functionalities. The two modes of coordination of R2PBR'2 to transition metals, κ<sup>1</sup> (P) and η<sup>2</sup> (PB), are covered, along with the applications of borylphosphine complexes in homogeneous catalysis.